checkbox-cli needs a missing checkbox.conf to work properly

[Betty Lin]

[Summary] checkbox-cli needs a missing checkbox.conf to work properly

[Steps to reproduce]
1. Install checkbox
2. Run some wireless auto tests

[Expected result]
wireless auto tests can be passed
[Actual result]
All wireless auto tests will fail because of "Error: No network with SSID 'ifname' found." or "Error: No network with SSID 'password' found."
When we checked the config by following command:
u@u-XPS-13-9380:~$ checkbox-cli check-config
Configuration files:
 - /etc/xdg/plainbox.conf
 - /etc/xdg/checkbox.conf (not present)
 - /home/u/.config/plainbox.conf (not present)
 - /home/u/.config/checkbox.conf (not present)
Variables:
Sections:
   [environment]
   BTDEVADDR=84:A6:C8:7D:BA:FD
   OPEN_AC_SSID=ubuntu-cert-ac-open
   OPEN_BG_SSID=ubuntu-cert-bg-open
   OPEN_N_SSID=ubuntu-cert-n-open
   ROUTERS=multiple
   SERVER_IPERF=192.168.158.9
   WPA_AC_PSK=insecure
   WPA_AC_SSID=ubuntu-cert-ac-wpa
   WPA_BG_PSK=insecure
   WPA_BG_SSID=ubuntu-cert-bg-wpa
   WPA_N_PSK=insecure
   WPA_N_SSID=ubuntu-cert-n-wpa
No validation problems found

It looks like the configurations can be found by checkbox-cli, but the tests need to reffer the configurations will be failed (for example: wireless auto)
Need to copy plainbox.conf to checkbox.conf in /etc/xdg and then the tests can run and passed.

[Betty Lin (bettyl)]

Automatically attached

[Betty Lin (bettyl)]

Automatically attached

[Betty Lin (bettyl)]

Automatically attached

[Jonathan Cave (jocave)]

Hopefully this bug has been addressed, please re-open if it's still an issue